Adjustment providing electromagnetic head mount



1953 M. s. TOWNSLEY 2,647,755

ADJUSTMENT PROVIDING ELECTROMAGNETIC HEAD MOUNT Fiied June 9, 1951 $2 wm#Z. n. j 1 0 km a,

Patented Aug. 4, 1953 ADJUSTMENT PROVIDING ELECTRO- MAGNETIC HEAD MOUNTMalcolm G. Townsley, Park Ridge, 111., assignor to Bell & HowellCompany, Chicago, 111., a corporation of Illinois Application June 9,1951, Serial No. 230,762

"Myinvention relates particularlyto a mount for an electromagnetic headsuch as is used in 'magnetic sound recordin and reproducing apparatus,and has fo r its objectthe provision of a simple, efie'ctive andconveniently adjustable mount for an electromagnetic head which providesadjustment of the head to properly angularly position the gapped poleportion of the head reference to the accompanying drawing forming a parthereof and in which- Figure 1 is a partial side elevation of a soundmotion, picture projecting machine embodying my invention and havingparts omitted and shown in section I i Figure 2 is a plan view of anelectromagnetic head carried on the mount of my invention;-

Figure 3 is an end elevation of the electromagnetic headand mount;

Figures 4 and 5 are side elevations of the electromagnetic head andmount and showing them in different adjustments; Y

. Figure 6 is a perspective view of the electromagnetic head carrier ofmy invention; and

Figure 7 is a side elevation of the electromagnetic head and a mountembodying another form of my invention.

Referring to the drawing, 1 designates a casing forming the base of asound motion picture projecting machine, see Figure 1. A rotatable shaft2 is carried with the easing, and a usual sound drum, indicated ate by adot and dash line, is carried on' the projecting end' of the shaft 2 forrotation therewith. A motion pic- "ture film strip, indicated at '4 bydot and dash lines, is trained about the drum 3 and is fed at a uniformrate about the sound drum, the drum guiding the film strip past "soundtranslating means for cooperation thereof with a sound track on the filmstrip. y l 4 l The projecting machine illustrated in Figure 1 isarranged either for magnetic recording or reprodutcion in cooperationwith a magnetic sound track on the film strip or for optical soundreproduction in cooperation with an optical soundtrack on the filmstrip, and includes a carriers mounted on the casing for pivotalmovement about the axis of the shaft 2 for alternately positioningoptical and magnetic sound translating means in cooperative relationwith the film strip. However, for the present pur- 4 Claims. (01.274-24) poses the carrier 5 may be considered as fixed in its magneticsound position as shown.

Two electromagnetic heads 6 are mounted on the carrier 5 in adjacentlyspaced relation about the pivotal axis of the drum 3 and are cooperativewith and inwardly of the sound record portion of the film strip t at thedrum, the gapped pole portions 1 of the heads facing outwardly from theaxis of the drum and the heads being resiliently mounted to yieldablyurge the gapped pole portions outwardly against the sound record portionof the film strip at the drum as shown in Figure 1, one of the headsconstituting an erase head and the other constituting a recording andreproducing head as is usual.

The mounting of each electromagnetic head comprises a stud 8 fixed onthe carrier 5 in parallelism with the shaft 2 and spaced a greaterdistance from the axis or the drum 3 than the radius of the drum, abored support block 9 pivotally engaged on the stud and secured inpivotally adjusted position thereon by a set screw II, a spring supportarm l2 having one end thereof secured on the support block 9 andextending in a radial plane of the axis of the drum 3 and havin theelectromagnetic head mounted on the free end thereof for pressing thegapped pole portion 7 of the head against the sound record portion ofthe film strip. This arrangement permits of an adequate spring lengthand adjustment of the spring arm to provide the desired pressure of theelectromagnetic heads against the film strip.

The structure above described is described and claimed in copendingapplication for United States Letters Patent of Frank J. Schuessler,Serial No. 217,843, filed March 2'7, 1951, for improvement in MagneticSound and Combined Optical and Magnetic Sound Translating Apparatus, andmy invention which pertains to the mounting of the electromagnetic heads6 on the spring support arms IE, will now be described.

Referring to Figures 2 to 6 inclusive, a carrier l3 of non-magneticmaterial has one end thereof provided with opposite slots 14 which areengaged between the spaced legs I5 of the core l6 of an electromagnetichead 6 with this end between the coils l1 and the gapped pole portion 1of the head to secure the head on the carrier. The carrier l3 extendslaterally of the head and its other end [8 is ofiset in the directionaway \J plane normal to that of the core l8 and extending transverselyof the core legs I5.

The free end portion 2! of a spring support arm 12 overlies the carriersurface [9 and extending along the same, is angled at the medial portionthereof, as designated at 22, to render the support arm end portion 2]angular and to provide the convex surface 23 thereof opposing the fiatcarrier surface I9. Spaced headed screws 24 are disposed on oppositesides of the medial portion of the support arm end portion 2-! and thecarrier end 28, and pass through apertures 25 in the support arm endportion and are screwthreaded into screwthreaded bores 26 in the carrierend Hi to secure the support arm end portion 2| and the carrier end [8together and thus mount the electromagnetic head 6 on the spring supportarm l2.

The screws 24 in cooperation with the convex and flat surfaces 23 and I9and flexure of the support arm end portion 2!, provide angularadjustment of the electromagnetic head 6 in the plane of the head coreit for conveniently adjusting the gapped pole portion 7 into properangular relation with the sound track portion of the film strip 4, andprovide this adjustment by varied fiexure of the support arm end portion2! of the spring support arm [2. Referring to Figures 4 and 5, the outerscrew 24 at the outer end of the support arm end por tion 2! firmlyclamps the outer end of the support arm end portion 2! onto the carrierend surface l9, and the other or inner screw it serves as an adjustmentscrew and is screwthreaded into the carrier end [8 only so far as isrequired to effect the desired adjustment of the electromagnetic head 6.Figure 4 shows the inner screw 26 at an outer adjustment thereof inwhich the support arm end portion 2| is flexed a relatively small extentand the gapped pole portion T of the head faces vertically, and Figure 5shows the inner screw 24 at an inner adjustment thereof in which thesupport arm end portion 25 is deformed a Referring to Figure '7, showinga modification of the invention, the free end portion 28 of the springsupport arm i2 is normally fiat, and the mounting surface 29 of the endl8 of the head carrier- 13 is angled at the medial portion thereof,

as designated at 3|, to render the surface 23 convex. This convexsurface 29 opposes the normally fiat surface 32 of the support arm endportion 28, and the headed screws 24, disposed on opposite sides of themedial portion of the support arm, end. portion 28 and the carrier end18 andi-ts surface 29 and passing through apertures. in the support. armend portion and screwthreaded into the carrier end I8, serve, incooperation with the convex and fiat surfaces 29 and 32 and fiexure ofposes as illustrated in Figures 4 and 5 and above described.

While Iv have thus described my invention, I

, the support arm end portion 2-8, the same pur- 4. do not wish to belimited to the precise details described, as changes may be readily madewithout departing from the spirit of my invention, but having thusdescribed my invention, I claim as new and desire to secure by LettersPatent the following:

1. In an electromagnetic head mount, the combination of anelectromagnetic head carrier, a spring support arm having a portionthereof overlying said carrier, the opposing surfaces of said carrierand arm comprising a convex and a flat surface, and spaced securingdevices for securing said carrier and arm together in the directionengaging said surfaces and disposed on opposite sides of the medialportion of said convex surface and, comprising adjustable meansproviding angular adjustment of said head with respect to said arm incooperation with said convex and fiat surfaces and fiexure of saidsupport arm portion.

2., In an electromagnetic head mount, the combination of anelectromagnetic head carrier, a spring support arm having a portionthereof overhzing. said carrier, the opposing surfaces of said carrierand arm comprising a convex and a fiat surface, and spaced securingdevices for securing said carrier and arm togetherin the directionengaging said surfaces and disposed on opposite sides of the medialportion of said convex surface and at least one of said securing devicescomprising a screw device providing angular adjustment of said head withrespect to said arm in cooperation with said convex and flat surfacesand flexure of said support arm portion.

In an electromagnetic head mount, the combination of an electromagnetichead carrier, a spring support arm having a portion thereof overlyingsaid carrier, the opposing surfaces of said carrier and arm comprising aconvex and a flat surface, and spaced securing devices for securing saidcarrier and arm together in the direction engaging said surfaces anddisposed on opposite sides of the medial portion of said convex surfaceand at least one of said securing devices comprising a headed screwpassing through said arm and 0 screwth-readed intosaid carrier andproviding angular adjustment of said head with respect to said arm incooperation with said convex and flat surtaces' and flexure of saidsupport arm portion.

4. In anelectromagnetic head carrier, the combination of anelectromagnetic head carrier, a spring. support arm having, a portionthereof overlying said carrier, the opposing surfaces of said carrierand arm comprising a convex and a flat surface, and spaced securingdevices for securing said carrier and arm together the directionengaging said surfacesand disposed on opposite sidesof: the medial?portion of convex surface and said securing devices comprising headedscrews passing, through said arm and screwthreaded into said. carrierand providing angular adjustmentoi' said head with respect to said armin cooperation withsaid convex and fiat-surfaces and fiexure of saidsupport arm.,portion.

MALCOLM G1. TOWNSLEY'.

Davis 'May 1 1'95]. Ham July 1 7-, 1 951 Number

